The present invention concerns a method for reducing the consumption of a stepping motor by automatically adapting the duration of each drive pulse supplied to the motor to the load that the motor is to drive.
The invention also concerns a device for controlling a stepping motor of a timepiece, for performing the abovementioned method.
A number of methods for reducing the consumption of a stepping motor have already been proposed.
French Pat. No. 2 200 675 for example proposes measuring the load which the motor is required to drive, by permanently measuring the current flowing in the winding of the motor when a drive pulse is applied to the winding and interrupting the drive pulse when the current passes through a minimum.
Detecting the minimum current value is difficult because of the parasitic noise which may be superimposed on the current measuring signal. This means that the known method is generally unreliable. In addition, when employed with some motors, and when the load which is to be driven by the motor becomes substantial, the current minimum disappears so that the known method can no longer be used.